The bill awaits the signature of Gov. John Hickenlooper, who supports the stoned-driving measure and is expected to sign it next week.

After the marijuana bill passed, Hickenlooper issued a statement lauding the driving standard as “a much-needed new tool to keep our highways safe from impaired drivers.”

Baker wants the court to step in and prevent the bill’s enactment. Because some users have higher blood levels of THC, the psychoactive ingredient in pot, the standard will be unequally applied, he said.

“I don’t feel they’re about getting impaired drivers off the road,” Baker told The Associated Press. “I feel it’s more of a law to infringe on a selected group of people.”

Colorado lawmakers struggled for three years to come up with stoned-driving standard because of just those concerns. Because blood THC levels vary based on the user, some feared that using them as an analogy to blood-alcohol limits might not be a fair gauge of impairment.

To address those concerns, the bill that passed the Legislature gives defendants more flexibility than they would face in a drunken-driving case. Defendants would be allowed to argue that even though they had elevated blood levels, they were not impaired. That line of defense isn’t available to someone who tested above legal alcohol driving limits.

Baker argues that the looser standard doesn’t go far enough to protect frequent marijuana users from wrongful DUI convictions. A paralegal and minister of a nondenominational church that consumes marijuana in religious rites, Baker said the pending bill should at least include exceptions for medical and spiritual users of the drug.